It is a dark time for the rebellion.  Although the Death Star has been destroyed, Imperial troops have driven the Rebel forces from their hidden base and pursued them across the galaxy.

Evading the dreaded Imperial Starfleet, a group of freedom fighters led by Luke Skywalker has established a new secret base on the remote ice world of Hoth.

The evil lord Darth Vader, obsessed with finding young Skywalker, has dispatched thousands of remote probes into the far reaches of space...

"In the wake of the success of STAR WARS, George Lucas' desire to create a nine-part saga set in that distant galaxy far, far away became viable and THE EMPIRE STRIKES BACK is a manifestation of that dream.

"The new motion picture is a further episode in an epic adventure spanning forty years.  The whole adventure is divided into three trilogies, with STAR WARS and THE EMPIRE STRIKES BACK as the first two parts of the middle trilogy."

- excerpt from the liner notes to the Empire Strikes Back soundtrack, 1980

STAR WARS EPISODE V: THE EMPIRE STRIKES BACK: fourth draft, dated 1978-1979

STAR WARS EPISODE V: THE EMPIRE STRIKES BACK: public version edited to match the final film release, published in 1980.
Not the actual shooting script.

"Skywalker, Skywalker.  And why do you come to walk my sky?  All your life have you looked away... to the horizon, to the sky, to the future."

- Yoda